feat: add authentication support and user model

- Updated `env.example` to include NextAuth configuration for authentication.
- Added `next-auth` dependency to manage user sessions.
- Introduced `User` model in Prisma schema with fields for user details and password hashing.
- Integrated `AuthProvider` in layout for session management across the app.
- Enhanced `Header` component with `AuthButton` for user authentication controls.

src/types/next-auth.d.ts

@@ -0,0 +1,31 @@
+import NextAuth from "next-auth"
+
+declare module "next-auth" {
+  interface Session {
+    user: {
+      id: string
+      email: string
+      name: string
+      firstName?: string
+      lastName?: string
+      avatar?: string
+      role: string
+    }
+  }
+
+  interface User {
+    id: string
+    email: string
+    name: string
+    firstName?: string
+    lastName?: string
+    avatar?: string
+    role: string
+  }
+}
+
+declare module "next-auth/jwt" {
+  interface JWT {
+    id: string
+  }
+}